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Allow new_connection to take an optional Seat. (NFC)

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This is working towards allowing the subsidiary SSH connection in an
SshProxy to share the main user-facing Seat, so as to be able to pass
through interactive prompts.

This is more difficult than the similar change with LogPolicy, because
Seats are stateful. In particular, the trust-sigil status will need to
be controlled by the SshProxy until it's ready to pass over control to
the main SSH (or whatever) connection.

To make this work, I've introduced a thing called a TempSeat, which is
(yet) another Seat implementation. When a backend hands its Seat to
new_connection(), it does it in a way that allows new_connection() to
borrow it completely, and replace it in the main backend structure
with a TempSeat, which acts as a temporary placeholder. If the main
backend tries to do things like changing trust status or sending
output, the TempSeat will buffer them; later on, when the connection
is established, TempSeat will replay the changes into the real Seat.

So, in each backend, I've made the following changes:
 - pass &foo->seat to new_connection, which may overwrite it with a
   TempSeat.
 - if it has done so (which we can tell via the is_tempseat() query
   function), then we have to free the TempSeat and reinstate our main
   Seat. The signal that we can do so is the PLUGLOG_CONNECT_SUCCESS
   notification, which indicates that SshProxy has finished all its
   connection setup work.
 - we also have to remember to free the TempSeat if our backend is
   disposed of without that having happened (e.g. because the
   connection _doesn't_ succeed).
 - in backends which have no local auth phase to worry about, ensure
   we don't call seat_set_trust_status on the main Seat _before_ it
   gets potentially replaced with a TempSeat. Moved some calls of
   seat_set_trust_status to just after new_connection(), so that now
   the initial trust status setup will go into the TempSeat (if
   appropriate) and be buffered until that seat is relinquished.

In all other uses of new_connection, where we don't have a Seat
available at all, we just pass NULL.

This is NFC, because neither new_connection() nor any of its delegates
will _actually_ do this replacement yet. We're just setting up the
framework to enable it to do so in the next commit.
This commit is contained in:
Simon Tatham
2021-09-13 17:17:20 +01:00
parent a08f953bd6
commit 6d272ee007
14 changed files with 465 additions and 21 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
otherbackends/telnet.c
View File

@ -626,8 +626,15 @@ static void telnet_log(Plug *plug, PlugLogType type, SockAddr *addr, int port,
backend_socket_log(telnet->seat, telnet->logctx, type, addr, port,
error_msg, error_code, telnet->conf,
telnet->socket_connected);
if (type == PLUGLOG_CONNECT_SUCCESS)
if (type == PLUGLOG_CONNECT_SUCCESS) {
telnet->socket_connected = true;
if (is_tempseat(telnet->seat)) {
Seat *ts = telnet->seat;
tempseat_flush(ts);
telnet->seat = tempseat_get_real(ts);
tempseat_free(ts);
}
}
}
static void telnet_closing(Plug *plug, const char *error_msg, int error_code,
@ -698,9 +705,6 @@ static char *telnet_init(const BackendVtable *vt, Seat *seat,
char *loghost;
int addressfamily;
/* No local authentication phase in this protocol */
seat_set_trust_status(seat, false);
telnet = snew(Telnet);
telnet->plug.vt = &Telnet_plugvt;
telnet->backend.vt = vt;
@ -740,10 +744,13 @@ static char *telnet_init(const BackendVtable *vt, Seat *seat,
*/
telnet->s = new_connection(addr, *realhost, port, false, true, nodelay,
keepalive, &telnet->plug, telnet->conf,
log_get_policy(logctx));
log_get_policy(logctx), &telnet->seat);
if ((err = sk_socket_error(telnet->s)) != NULL)
return dupstr(err);
/* No local authentication phase in this protocol */
seat_set_trust_status(telnet->seat, false);
telnet->pinger = pinger_new(telnet->conf, &telnet->backend);
/*
@ -797,6 +804,8 @@ static void telnet_free(Backend *be)
{
Telnet *telnet = container_of(be, Telnet, backend);
if (is_tempseat(telnet->seat))
tempseat_free(telnet->seat);
strbuf_free(telnet->sb_buf);
if (telnet->s)
sk_close(telnet->s);